As the digital printing technique has been developed, counterfeit cases of a bill, securities, a passport and the like have also been increasing, causing a problem in fraud or lowering the level of security. Even with progress in the information processing technology, security countermeasures have not been sufficiently developed yet, such that cases of unauthorized withdrawal by skimming a cash card are still mushrooming. Moreover, the security risk of product whose authentication means still depends on a person, such as counterfeit cases on a high priced goods like a medical product and a brand name product, are left unsolved.
Countermeasures of counterfeits of those authenticated by a machine such as a bill or a cash card authenticated by an automatic vending machine or an automated teller-machine have been developed and some methods have been already used.
For example, as a technique of preventing counterfeit of bill, a hologram, a watermark, a latent image pattern, a pearl ink, a micro character, a special light-emitting ink, an intaglio and the like are known. Authentication with them is performed in the automatic vending machine or the automated teller-machine (Non-Patent Document 1).
As a technique of preventing unauthorized withdrawal using a cash card, a user authentication using a biometrics (living body feature) such as a fingerprint or a vein is performed (Non-Patent Document 2).
Further, an IC chip attached to an ID card or a credit card or an RFID tag applied to a label are also a type of preventing means of counterfeit (Non-Patent Document 3).
[Non-Patent Document 1]
A trend of security techniques for printing matter, Sharp Technical Journal vol. 89, pp. 11-14, 2004
[Non-Patent Document 2]
Biometrics security using veins, The Journal of the Institute of Electronics, Information and Communication Engineers, vol. 89, No. 1, pp. 40-45, 2006
[Non-Patent Document 3]
RFID handbook-principle and applications of non-contact IC card, Daily Industry Newspaper, 2001
Even a technique of preventing counterfeit has been developed in the above-mentioned preventing means of counterfeit, a technique of reproducing has also developed, and thus, more precise counterfeit cases are still mushrooming for the bill, for example. As there many cases a person authenticates an object, counterfeited bills may be circulated even they are not precise. The user authentication means for a cash card is not practical as it takes much time and cost to set in all the machines. The IC chip or the RFID tag can be counterfeited by steeling information, and thus, those applied with them may also be counterfeited.
The present invention is adapted in view of the above-mentioned conventional problems and the problem to be solved is to provide a sign authentication system and a sign authentication method that are hardly ever counterfeited even if the system of the authentication is known, without requiring a special device such as an IC chip for authenticating originality.